The family of a great-gran killed after being hit by a speeding police outrider escorting the Duchess of Edinburgh today blasted his acquittal, saying: "Police are above the law." Helen Holland, 81, was struck crossing a road at a "green man" signal by a motorcycle escorting the Duchess of Edinburgh. Last week, PC Christopher Harrison, 68, was cleared of causing death by dangerous driving. Met escort riders are allowed to run red lights and break speed limits if it is necessary and safe. But